不同比例苎麻和象草混合青贮饲料品质比较研究

摘要

本试验旨在比较不同比例苎麻和象草混合青贮饲料品质,为调制高品质的苎麻青贮饲料提供理论依据.以苎麻和象草为原料,按苎麻和象草干物质比例为2∶8、3∶7、4∶6和10∶0( A、B、C、D组)进行混合青贮,青贮45 d后测定混合青贮饲料的营养成分、青贮发酵品质及瘤胃降解特性.结果表明:1)单独青贮苎麻的丁酸含量高,弗氏评分等级仅为"劣" ,添加象草进行混合青贮可显著提高苎麻青贮饲料的品质;混合青贮饲料的营养价值随象草比例增加而显著提高,其青贮发酵品质在混合青贮比例高于70%时显著降低( P＜0.05) ;苎麻和象草以2∶8的比例混合青贮时其青贮饲料品质最佳,中性洗涤纤维( NDF)和酸性洗涤纤维( ADF) )含量和氨态氮/总氮较低,而粗蛋白质和乳酸含量较高. 2) A、B、C组混合青贮饲料在6～72 h的干物质、有机物、粗蛋白质、NDF和ADF等营养物质在瘤胃中的降解率随其在瘤胃停留时间的延长而逐渐增加;对于干物质、有机物、ADF而言,A组降解率最高,C组次之,B组最低.对于粗蛋白质、NDF而言,3组之间差异不显著( P＞0.05) ,但 A 组混合青贮饲料的粗蛋白质、NDF有效降解率最高.综合分析,建议在生产中苎麻和象草混合青贮的最适比例为2∶8.%Effect of different mixing ratios on the quality of ramie and grassy silage was discussed, which pro?vided a theoretical basis for the preparation of high quality ramie silage. Ramie and grassy were used as raw materials for mixed silage according to the dry matter ratio of ramie to grassy: 2∶8, 3∶7, 4∶6 and 10∶0 ( A, B, C and D groups). The results showed as follows: 1) individual silage ramie had a high butyric acid content, and the Freund’s rating was only " inferior" , and mixed silage by adding grassy could significantly improve the fermentation quality; the nutritional value of mixed silage was increased significantly with the increase of the ratio of grass, and the silage quality decreased significantly when the mixed silage ratio was higher than 70%( P＜0.05) ; the quality of silage was the best when ramie to grassy mixed ratio at 2∶8, besides the fiber compo?nents ( neutral detergent fiber and acid detergent fiber) and ammonia nitrogen/total nitrogen were lower and the crude protein and lactic acid contents were higher than other mixing ratios. 2) In the rumen degradation charac?teristics experiment, the degradation rate of nutrients such as dry matter, organic matter, crude protein, neutral detergent fiber and acid detergent fiber of mixed silage in the rumen of A, B and C groups was gradually in?creased with the prolongation of the rumen staying time from 6 to 72 h; for dry matter, organic matter and acid detergent fiber, the degradation rate of group A was the highest, followed by group C, the lowest was group B. There was no significant difference in the degradation rate of crude protein and neutral detergent fiber among three groups ( P＞0.05) , but the crude protein and neutral detergent fiber of mixed silage of group A had the highest effective degradation rate. Considering comprehensively, it is recommended that the optimum ratio of ramie to grassy mixed silage is 2∶8 in production.[ Chinese Journal of Animal Nutrition, 2019, 31(6) :2830?2841]